Quick-release grinding machine coupling and improved abrading device for use therewith



Now-3,1970 R. 1.. JOHNSON 3,537,332

, QUICK-RELEASE GRINDING CHINE UPLING AND IMPROVED v ABRADING DEVI F U THEREWITH Filed Sept. 0, 1968 m figzl- Fig-2- United States Patent US. Cl. 51376 7 Claims ABSTRACT OF THE DISCLOSURE A quick-release grinding machine coupling having a non-circular seat for quick releasably connecting an abrading device, having a complementary non-circular opening, to the shaft of a grinding machine.

This invention relates to a coupling for power-driven grinding or sanding machines, and more particularly to a quick-release coupling for such a machine which facilitates the attachment to and removal of abrading devices from such machines, and also an improved abrading device for use therewith.

While the improved coupling and abrading device of the present invention is intended for use with a wide variety of power-driven grinding machines, they are especially advantageous in connecting with electrically driven, manually operated grinding and sanding machines used in carrying out the shaping and finishing of metal surfaces. Hitherto, abrading devices have been attached to such machines by means of a back-up pad carried by a stud, the abrading device being held-against the back-up pad by a nut threaded on the stud. Arrangements have been provided to facilitate the attachment and removal of the back-up pad assembly with the abrading device, from the grinding machine; however, the arrangements hitherto provided for removing a used abrading device and replacing it with another have left much to be desired. Hitherto, to replace an abrasive disc on a grinder, it was necessary for the operator to use a tool such as a wrench to loosen a retaining nut while at the same time locking the shaft or spindle of the grinder against rotation. Not only was this operation time consuming, but it often resulted in injury to the fingers of the operator because of the tendency of the wrench to slip from the retaining nut which is usually excessively tightened by the torque developed when the machine is in use.

It is therefore a principal object of this invention to provide a grinding machine with an improved coupling which makes possible quick replacement of an abrading device such as abrasive discs, grinding wheels or the like.

Another object is to provide such an improved grinding machine coupling which not only makes possible the rapid attachment and removal of an abrading device, but which, though it is of relatively simple construction, is capable of relatively long trouble-free operation under the severely adverse conditions usually created incident to the operation of a grinder.

Further objects and advantages of the present invention will be apparent from the following detailed description of a preferred embodiment thereof when read in conjunction with the accompanying drawing in which:

FIG. 1 is a vertical cross sectional view of a grinder coupling constructed in accordance with the present invention, the spindle or output shaft of the grinder being shown broken away for convenience and the grinder body being omitted;

FIG. 2 is a cross sectional view thereof taken through the line 2-2 of FIG. 1; and

FIG. 3 is a top plan view of the stud assembly of the coupling removed from the receiver assembly.

Referring now to the drawing in detail, shaft 10' is the output shaft or spindle of any conventional power-driven grinder, spindle 10 being broken away and the remainder of the grinder being omitted because the details thereof are well known in the art and form no part of the present invention.

As shown in the drawing, my improved grinder cou pling comprises two assemblies, a receiver assembly 11 and a stud assembly 12. The receiver assembly 11 comprises a generally cylindrical receiver 13 having an axial bore 14 formed therethrough which is threaded at one end, the upper end as viewed in FIG. 1. A threaded plug 15 carrying a spring 16 is threaded into the bore 14 of the receiver 13. A slot 17 is formed in the wall of the receiver 13 forms a keyway which extends from one side into communication with the receiver bore 14. Two non-radial parallel bores 18 extend from the opposite side of the receiver 13 into communication with the keyway 17. A bifurcated key 19 is slideably mounted in the keyway 17 with its arms 19A extending through the bores 18. A retaining member 20, connected to the ends of arms 19A by means of bolts 21 serves to retain a pair of springs, one on each of the arms 19A, seated in enlarged diameter portions 23 of the transverse bores 18. The enlarged portions 23 of the bores 18 communicate with one another thereby providing a recess 23A for the ends of the keyway arms 19A and retaining member 20. The length of the key arms 19A is such that under the influence of the springs 22, the key 19 is urged far enough to the left so that its web portion extends substantially into the axial receiver bore 14 to engage and lock the stud assembly 12.

As viewed in FIG. 1, the lower end of the receiver 13 has a counterbore 24 formed therein which is non circular in transverse cross section. In the present instance, the walls forming the counterbore 24 form an equal-sided triangle, when viewed in cross section, the center of which lies on the vertical axis of the bore 14. An annular flange 25 on the receiver 13 extends peripherally about the outer end of the counterbore 24, and is formed with an annular chamfer indicated at 26 to receive a complementary portion of the stud assembly 12 with an abrasive disc seated thereon.

As shown in FIG. 1, the stud assembly 12 is conveniently of one-piece construction having a cylindrical head portion 27 adapted to fit within the receiver bore 14. At its opposite extremity, the stud assembly 12 has an an nular base portion 28. The base portion 28 is radially outwardly tapered to provide an inclined annular seat 29 which is substantially complementary to the annular chamfer 26 formed on the flange 25. An intermediate portion 30 extends between the base portion 28 and the head portion 27, and is non-circular in cross section to seat within the non-circular counterbore 24 of the receiver. As is most clearly shown in FIG. 3, the intermediate portion 30 is triangular in cross section, the sides forming an equilateral triangle for an easy mating fit within the triangular counterbore 24.

The head portion 27 has an annular groove 31 formed therein forming an annular shoulder 32. The length of the head portion 27 is such that with the stud assembly 12 seated in receiver 13, the head portion extends across the keyway 17, and the lip of the key 19 seats in groove 31 against the shoulder 32 with the head portion 27 compressing spring 16. To facilitate insertion of the stud assembly 12 to its latched position in the receiver 13, the leading end of the head portion 27 and the lip of key 19 are broken or rounded as indicated so that the key 19 is forced back by the advancing head of the stud assembly thereby compressing the springs 22.

A conventional back-up pad 33 formed of rubber or other suitable material is connected to the receiver flange by bolts (not shown) or other convenient means. As is well known, the diameter of the back-up pad depends upon the size of the abrading device to be used and is usually somewhat smaller.

As illustrative of the present invention, an abrading device in the form of an abrasive disc 34 having a fiber backing coated with a suitable abrasive on its working face is shown mounted in the coupling in FIG. 1 and positioned on the stud assembly 12 in FIG. 3. Any of a wide variety of abrading devices such as abrasive discs, grinding wheels or the like can be attached by means of my coupling to the grinder. It is only necessary that the abrading device be formed with a non-circular hole which conforms to the non-circular configuration of the receiver counterbore 24 and the intermediate portion of the stud assembly. While the noncircular configuration shown and described herein is that of an equilateral triangle, it is to be understood that other non-circular configurations can be used. Any desired shape, for example, a polygonal shape such as a square, pentagon, etc., or a star shape can be used which effectively prevents the abrading device from rotating relative to the coupling.

In use, the desired abrading device 34 having a circular outer periphery and an equilateral triangular hole to permit it to seat on the stud assembly base portion 28, is placed thereon as shown in FIG. 3, and then the stud assembly carrying the abrading device is inserted into the receiver assembly 11 where it is locked in place. When the grinder is energized, rotation of the grinder shaft 10 is transmitted through the receiver 13 and stud assembly 12 to the abrading device 34 because substantially all relative rotational motion between the abrading device 34, the stud assembly 12 and the receiver assembly 11 is effectively prevented by the non-circular hole 35, the conforming non-circular shape of the intermediate portion 30, and the counterbore 24.

When the abrading device 34 requires replacement, it is only necessary to press in the retainer 20, compressing springs 22 and shifting the key 19 far enough to clear the shoulder 30, whereupon spring 16 urges the stud assembly far enough along the bore 14 so that when the link 20 is released, the stud assembly is no longer in position to be latched by the key 19, and removal of the stud assembly and the worn-out abrading device is facilitated thereby. Thus, no wrenches or other tools are required, and replacement of the abrading device can be rapidly carried out.

A further advantage of my grinder coupling resides in the arrangement of the bifurcated key 19 with two substantially equal compression springs, one on each arm of the key which ensures free operation of the key 19 in its keyway 17 and the counterbores 23 in spite of the adverse conditions created by the metal dust generated in grinding.

To provide the improved abrading device of my invention, it is not necessary to disturb the peripheral shape of the abrading device, which may, for example, be circular, oval or polygonal, or the area on which the usual abrading material is provided. In the case of abrasive discs having backings formed of such materials as cloth, paper, vulcanized fiber or the like, usually it will be sufficient to form the desired non-circular hole in the central web portion of the disc. In some instances, when the disc backing is too weak, it may be necessary to reinforce the central portion of the backing with the same or other suitable material through which the non-circular opening is provided. In the case of such abrading devices as grinding wheels, they may be formed in the usual way but with the desired, centrally located, non-circular opening.

By providing a non-circular hole through the abrading device and a corresponding non-circular seat on the coupling, it is no longer necessary, as was hitherto the case, to provide an arrangement for positively clamping the side surfaces of the abrading device in the grinder coupling to prevent the abrading device from rotating relative to the coupling and grinder shaft. While I have described the preferred embodiment of my invention, it is to be noted that in a less preferred embodiment the noncircular seat for the abrading device, instead of being formed on the removable coupling, can be formed on the receiver assembly around the open end of its axial bore. In that event the stud assembly is provided with a cylindrical head portion which merges with the stud base, the latter having a larger diameter than the non-circular seat to retain the abrading device 34 in fixed removable relation on the coupling.

The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.

What I claim is:

1. A grinding machine coupling for connection to the rotatably driven shaft of a grinder comprising two assemblies including a receiver assembly and a stud assembly, said receiver assembly having a first elongated bore formed therein having at least one open end, one of said assemblies having a non-circular seat formed therein for receiving an abrading device having a central non-circular hole formed therethrough substantially matching said non-circular seat, means for removably locking said stud assembly in said first bore, said stud assembly including means for retaining said abrading device on said noncircular seat, and means for connecting said coupling to said grinder shaft and for imparting its rotation to said non-circular seat.

2. A grinding machine coupling adapted to be fixed to the rotatably driven shaft of a grinder, comprising a receiver having a first elongated bore formed therein open at at least one end thereof, said receiver being adapted to be fixed to said grinder shaft with the longitudinal axis of said bore aligned with the axis of said shaft, said first bore having at least a portion thereof adjacent the open end thereof non-circular in transverse cross section, a stud assembly having a base portion for retaining an abrading device having a central non-circular hole formed therethrough substantially matching the transverse cross-sectional shape of the non-circular portion of said first bore, said stud assembly having an intermediate portion adjacent said base portion thereof, said intermediate portion being non-circular in transverse cross section with its cross-sectional shape complementary to that of said noncircular portion of said first bore, said non-circular intermediate portion being removably seated in the non-circular portion of said first bore for removably connecting said abrading device to said receiver, and means for locking said stud assembly in said receiver, whereby rotation of said receiver by said grinder shaft is imparted to said abrading device.

3. A grinding machine coupling as set forth in claim 2 in which said receiver has a transverse keyway formed therein communicating with said first bore spaced from the open end thereof, said stud assembly has a head portion extending from the side of said intermediate portion away from said base portion and across said keyway, and said stud assembly locking means includes a key slideably mounted in said keyway for releasably engaging said head portion.

4. A grinding machine coupling as set forth in claim 3 in which said stud assembly locking means includes resilient means urging said key into engagement with said head portion.

5. A grinding machine coupling as set forth in claim 4 in which said receiver has a pair of spaced parallel openended bores formed transversely therein and communicating with said keyway, said key is bifurcated and positioned with its arms extending one in each of said transverse bores, said key engaging said head portion on one side of the axis of said first bore, said key arms projecting from said transverse bores on the other side of said axis, said resilient means includes a pair of springs one associated with each of the projecting portions of said key arms on said other side of said axis, and retaining means connecting said key arms and retaining said springs under compression.

6. A grinding machine coupling as set forth in claim 5 in which said head portion has a groove formed therev in to receive said key in locking engagement with a shoul- References Cited UNITED STATES PATENTS 1,693,163 1 1/1928 Schacht 51-379 2,685,155 8/1954 Kuzma et a1. 51401 3,270,468 9/1966 Block et a1. 51358 3,376,675 4/ 1968 Hutchins 51376 3,436,875 4/1969 Cheney 51-376 OTHELL M. SIMPSON, Primary Examiner US. Cl. X.R. 51-401 

